The protagonist of MGS2 is a young rookie agent named Raiden.He is supported by his commanding officer, the Colonel, and Rosemary, his girlfriend. Allies formed on the mission include Lt. Junior Grade Iroquois Pliskin, a Navy SEAL of mysterious background who provides his knowledge of the facility; Peter Stillman, an NYPD bomb-disposal expert; Otacon, a computer security specialist; and a "cyborg ninja" imitating Gray Fox's persona, but calling itself Mr. X.
The antagonists of the piece are the Sons of Liberty, a group of terrorists who seize control of the Big Shell Disposal Facility, including anti-terror training unit Dead Cell, and a Russian mercenary force. The Dead Cell team members are Vamp, an immortal man exhibiting vampire-like attributes; Fatman, a rotund man with an exceptional knowledge of bombs; and Fortune, a woman capable of cheating death by apparent supernatural means. The leader of Sons of liberty claims to be Solid Snake, previously declared dead after a terrorist attack. Assisting the Sons of Liberty are Olga Gurlukovich, commander of a rogue Russian mercenary army and Revolver Ocelot, a disenfranchised Russian nationalist and former FOXHOUND agent and the henchman of Solidus Snake.
Other characters include Emma Emmerich, Otacon's stepsister and a computer wiz-kid; Sergei Gurlukovich, Ocelot's former commanding officer and Olga's father; President James Johnson, held hostage by the Sons of Liberty; and DIA operative Richard Ames. Solid Snake returns, along with Liquid Snake, who communicates via Ocelot through unknown means, and a third Snake, Solidus, is introduced.
